5-string Carl Thompson inspired bass, "Black Rainbow/Night Rainbow"

Well, I'll start out by wearing my heart on my sleeve. Carl Thompson has been an inspiration to me for many many years and it was he that inspired me to start building instruments nine years ago. This is more of a tribute build (well, two actually but we'll get to that later) incorporating techniques and materials from my own arsenal which I know Carl does not use in his own. As much as I would love to commission Carl make me a bass, this is not going to be a reality anytime soon.

As mentioned, this is actually two builds. The first is a fully-fledged build, however it is a practice model for the "actual" instrument. I am using a fair number of templates, jigs and techniques which are being practiced on the first instrument and applied to the second. So, without further ado the specs of the eventual build:

35"-36" light compound scale set neck

30mm thick chambered Black Alder body (!)

Birch neck with Wenge laminations

Wenge fingerboard laminated with carbon fibre veneer

Seymour Duncan SMB-5a Music Man pickup

Homebrewed "70s" MM pre-amp

Custom milled and powder coated brass bridge

Carbon fibre neck reinforcement

Carbon fibre laminated cavity covers

Side mounted Neutrik jack

Black Gotoh Ultralights or Schaller BM Lights

LED sidemarkers and diffused pinstripe headstock logoplate

More on this spec later on as there are many details I will be tweaking. Any input on the choice of these two tuners types would be welcomed.

The first build is the same design but obviating the compound scale for a single 35" scale, a Hipshot D style bridge and no carbon fibre accents around the instrument. We're talking Sapele, Wenge and Ebony to go under a nice oil finish. Pretty straightforward, and it should be since it is a "practice" instrument.

Firstly, the CAD plan. These always start with a simple flattened top-down sketch. None of the horizontal lengths take into account perspective of course so geometric distortions exist. I usually use this to produce cross-sections from the side. A real top-down view would be of no practical use, however this method is perfect for producing printable templates (until I start making CNC cut templates).

As can be seen, the instrument is a derivative of Carl's scroll basses incorporating the string-through "fishtail". The scroll itself will be the 3D-type scroll which curls up from the inner point towards the front. This of itself will be most of the learning work!

A shopped mockup of the basses final appearance:

Okay, so the build is currently a couple of weeks in already so I'll recap.

The template for the body was printed onto 4x sheets of A4 with alignment reference marks before bonding them onto a sheet of 18mm thick plywood. In hindsight I should have used 5-8mm thick MDF as this material is more forgiving for adjustment and finessing and THEN transferring that to plywood. But hey.

The lower half of the body is pretty much a 45° bevel throughout, petering off to where I planned in the square plate for the jack (not drawn in the CAD plan). This was done on the table router before cleaning up with papers. The body surfaces are taped up to protect them since it is now a hair over 31mm thick. Stray scratches could easily put a dent in my day, no joke intended.

This is where we stand as of today. The upper bevels were roughed in using a 45° bevel cutter on a router table to remove as much stock by machine as possible to save on the hand work. From hereonin it is rasp, scraper and paper baby.

In other news, the headstock has been shaped on the pin router and the Ebony trapezoidal inlay on the headstock marked out ready for cutting and inlaying.

Wow, you must have a bad run of things with Sapele! I get most of the movement out whilst still in the board and sometimes it just wants to get out and party when in smaller pieces, but I still don't get a 50% party piece rate! Perhaps me soaking up losses from the board.

Wow, you must have a bad run of things with Sapele! I get most of the movement out whilst still in the board and sometimes it just wants to get out and party when in smaller pieces, but I still don't get a 50% party piece rate! Perhaps me soaking up losses from the board.

Click to expand...

I think it has more to do with the ridiculous humidity we have here. We avg. 85% + through most of the summer.